1. Field of the Invention
This invention relates to heat exchangers and more particularly to the simultaneous installation of rows of U-shaped tubes into heat exchangers.
2. Description of the Prior Art
U-shaped tubes are in common use and are installed one tube at a time with the tube sheets vertically oriented and the tubes disposed horizontally as they are slit through the holes in the support plates. Installing complete rows of horizontal tubes has been tried but was not successful as the frictional force between the tubes and the support plates made it difficult to slide the complete rows of tubes through the support plates and into the tube sheet. U-shaped tubes are often manufactured at one plant and installed in heat exchanger in another location this is particularly true when a large number of special alloyed tubes are involved. Shipping containers for the tubes are normally wooden crates, which subject the tubes to frequent damage from nails and from bending and denting as the crates are easily damaged when handling with large mechanical equipment as is required, when the tubes are long.
Another problem stemming from the normal manufacture process of bending the tubes at one location and installing them in a heat exchanger at a distant location is if the tubes are not properly bent this will not be discovered until they are being installed in the heat exchanger.
In a plant where several heat exchangers are being built, a damaged tube can be replaced by borrowing a tube from another job, however, in a field retubing application extra assurance is required to insure that all the tubes are of the proper size and none are damaged during the crating and shipping operation as there are no spare tubes at the site and a damaged tube would seriously delay the retubing operation.